The present invention relates generally to piston-type hydraulic accumulators and more particularly to a hydraulic accumulator in which it may be determined whether a predetermined minimum of retained energy exists for proper operation thereof.
In the past, there was no way of determining how much energy or working gas pressure existed in a hydraulic accumulator. Since the pressure of the gas was dependent upon the hydraulic system pressure, until the piston bottomed out due to the lack of sufficient gas pressure, there was no way of telling whether a sufficient gas pressure existed in the accumulator to be satisfactory for proper operation of the hydraulic circuit. Thus, the first indication of a lack of sufficient energy or gas pressure was sometimes indicated by the failure of the accumulator to operate properly and a catastrophic failure of some other component in the hydraulic system.
Since there was no way of determining the actual gas pressure, it was a general practice to pressurize the accumulator when the hydraulic circuit was inoperative and to provide a safety factor in the form of a gas overcharge.